This 'tutorial' is a more general approach to some of the concepts of airbrushing and colouring that I have learnt, as opposed to a very specific step by step example. Hopefully you will learn more this way.

Adding Structure to a Shape

Basically airbrushing / colouring in Photoshop is giving details to an image. The way the details are created is by adding highlights, midtones, shadows and colour. The results can be simply cosmetic, or add quite a bit of structure to an image.

An example:

The hightlights (generally wider, more gradual and more dramatic than shadows) in that example make the shape seem quite three dimensional. Because of the closeness of highlight to shadow the effect is one where the physical attributes of an object change sharply. A more gental transition would look something like this:

As you can see the lighting changes have a two main attributes that make the appearance of the shape less '3D' and generally more flat. They are that

1: the shadows are not as dark, and the hightlights are not as bright, and

2: the darkest part of the shadow is not as close to the brightest part of the highlight. The less gradual the transition between light and dark sharper the physical appearance you are trying to map.

The use of midtones (the colour between highlight and shadow) gives a less dramatic appearance.

The dodge tool is used for adding highlights (set the mode to highlight) and the burn tool is used for adding....wait for it....shadows. Holding the ALT key while brushing will do the inverse action of which ever tool you are using, and can save time avoiding swapping tools constantly.

As with everything in life (getting a job, being taller, loosing weight) airbrushing will be MUCH easier with a graphics tablet and pen. Everything is far more intuitive !

General Brushing Method

You should brush lightly building to the harsher points of the lighting effects. Rounded brush strokes, combined with the smudge tool will help provide smooth gradiants between colour intensities.

For highlights I prefer to work with the strokes buiding onto the main highlight. Start softer (if using a tablet) and increase pressure towards the point of the highlight.

Shadow is basically the same, concentrate the brush on the darkest parts and use the smudge tool to spread the darker pixels smoothly.The blur tool can also be usefull.

Specific "How to's"

1: Making a dint.

The shading methods to make a dint like appearance in a surface is to have the shadow above the highlight. As usual work the extremes of the two to be close together.Notice the example :

2: Making a ridge

This is basically the opposite of a dint. Put the highlight above the shadow and marvel in awe at you're new ridge.For a sharp ridge use the lasoo tool and select a shape (only you'dre edge need be accurate, after that just select a big enough area to encompass all of you're shading) to highlight in. After the highlighting invert the selection and do the shadow on the other side.

Example :

If you want a more gentle ridge (usually looks better in my opinion) do the same with either a feathered selection, or no selection at all to allow more gradual shading differences.

A good use of this gradual ridge might be folds in a material, or wringkly skin

Example :

The adaptaion of these specific methods can produce many different effects, that you will figure out you're self pretty easily if you can understand my giberish.

Colouring a Drawing

To make life easier for you're self when you get into photoshop try to draw with solid single lines rather than alot of line mess. The first step after you draw the drawing is to scan it. Scanning to Black and white, and at a higher resolution if you wish to print later are good idea's.

After the scan open you're drawing in photoshop and press Ctrl + L to modify the levels (Black and white). Bring the two colour pointers closer together to help remove the 'noise' that is usually on hand drawings.

Here is my drawing after modified levels :

Set the blending mode of layers above the drawing to multiply to allow the black linework to show through easily and more accurately.

Now with you're magic wand, and a tolerance level that suits what you want, select a shape in the drawing.In a new layer fill it with the colour you want, and begin adding details / structure as described on the first page of this tutorial.

It can be a good idea to create a channel for selections made in colouring. It ensures editability later (especially if you accidentally save a flattened version of the image). To make a new channel ensure you have the selection of the area go to the channels tab and press the button, then alt + backspace to fill the area white.

Now add the lighiting and details

recommed a new layer for each distinct section of the drawing.

That should be enough to get you started with the concepts of airbrushing and colouring a drawing. Wheather a colouring be mearly making something black and white have colour, or if it makes structural changes to the image it's self is up to you, and dependant on how much detailing you put into it.